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Disable transformation of select of two loads to a select of address and then a load if the 

loads are not in the default address space because the transformation discards src value info.

llvm-svn: 93180
This commit is contained in:
Mon P Wang 2010-01-11 20:12:49 +00:00
parent e3e76e2a69
commit ec57c81e64
1 changed files with 41 additions and 28 deletions
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69
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -5792,35 +5792,48 @@ bool DAGCombiner::SimplifySelectOps(SDNode *TheSelect, SDValue LHS,
if (LLD->getMemoryVT() == RLD->getMemoryVT()) {
// FIXME: this discards src value information. This is
// over-conservative. It would be beneficial to be able to remember
// both potential memory locations.
// both potential memory locations. Since we are discarding
// src value info, don't do the transformation if the memory
// locations are not in the default address space.
unsigned LLDAddrSpace = 0, RLDAddrSpace = 0;
if (const Value *LLDVal = LLD->getMemOperand()->getValue()) {
if (const PointerType *PT = dyn_cast<PointerType>(LLDVal->getType()))
LLDAddrSpace = PT->getAddressSpace();
}
if (const Value *RLDVal = RLD->getMemOperand()->getValue()) {
if (const PointerType *PT = dyn_cast<PointerType>(RLDVal->getType()))
RLDAddrSpace = PT->getAddressSpace();
}
SDValue Addr;
if (TheSelect->getOpcode() == ISD::SELECT) {
// Check that the condition doesn't reach either load. If so, folding
// this will induce a cycle into the DAG.
if ((!LLD->hasAnyUseOfValue(1) ||
!LLD->isPredecessorOf(TheSelect->getOperand(0).getNode())) &&
(!RLD->hasAnyUseOfValue(1) ||
!RLD->isPredecessorOf(TheSelect->getOperand(0).getNode()))) {
Addr = DAG.getNode(ISD::SELECT, TheSelect->getDebugLoc(),
LLD->getBasePtr().getValueType(),
TheSelect->getOperand(0), LLD->getBasePtr(),
RLD->getBasePtr());
}
} else {
// Check that the condition doesn't reach either load. If so, folding
// this will induce a cycle into the DAG.
if ((!LLD->hasAnyUseOfValue(1) ||
(!LLD->isPredecessorOf(TheSelect->getOperand(0).getNode()) &&
!LLD->isPredecessorOf(TheSelect->getOperand(1).getNode()))) &&
(!RLD->hasAnyUseOfValue(1) ||
(!RLD->isPredecessorOf(TheSelect->getOperand(0).getNode()) &&
!RLD->isPredecessorOf(TheSelect->getOperand(1).getNode())))) {
Addr = DAG.getNode(ISD::SELECT_CC, TheSelect->getDebugLoc(),
LLD->getBasePtr().getValueType(),
TheSelect->getOperand(0),
TheSelect->getOperand(1),
LLD->getBasePtr(), RLD->getBasePtr(),
TheSelect->getOperand(4));
if (LLDAddrSpace == 0 && RLDAddrSpace == 0) {
if (TheSelect->getOpcode() == ISD::SELECT) {
// Check that the condition doesn't reach either load. If so, folding
// this will induce a cycle into the DAG.
if ((!LLD->hasAnyUseOfValue(1) ||
!LLD->isPredecessorOf(TheSelect->getOperand(0).getNode())) &&
(!RLD->hasAnyUseOfValue(1) ||
!RLD->isPredecessorOf(TheSelect->getOperand(0).getNode()))) {
Addr = DAG.getNode(ISD::SELECT, TheSelect->getDebugLoc(),
LLD->getBasePtr().getValueType(),
TheSelect->getOperand(0), LLD->getBasePtr(),
RLD->getBasePtr());
}
} else {
// Check that the condition doesn't reach either load. If so, folding
// this will induce a cycle into the DAG.
if ((!LLD->hasAnyUseOfValue(1) ||
(!LLD->isPredecessorOf(TheSelect->getOperand(0).getNode()) &&
!LLD->isPredecessorOf(TheSelect->getOperand(1).getNode()))) &&
(!RLD->hasAnyUseOfValue(1) ||
(!RLD->isPredecessorOf(TheSelect->getOperand(0).getNode()) &&
!RLD->isPredecessorOf(TheSelect->getOperand(1).getNode())))) {
Addr = DAG.getNode(ISD::SELECT_CC, TheSelect->getDebugLoc(),
LLD->getBasePtr().getValueType(),
TheSelect->getOperand(0),
TheSelect->getOperand(1),
LLD->getBasePtr(), RLD->getBasePtr(),
TheSelect->getOperand(4));
}
}
}